--- id: known-issues title: SQL-based ingestion known issues sidebar_label: Known issues --- :::info This page describes SQL-based batch ingestion using the [`druid-multi-stage-query`](../multi-stage-query/index.md) extension, new in Druid 24.0. Refer to the [ingestion methods](../ingestion/index.md#batch) table to determine which ingestion method is right for you. ::: ## Multi-stage query task runtime - Fault tolerance is partially implemented. Workers get relaunched when they are killed unexpectedly. The controller does not get relaunched if it is killed unexpectedly. - Worker task stage outputs are stored in the working directory given by `druid.indexer.task.baseDir`. Stages that generate a large amount of output data may exhaust all available disk space. In this case, the query fails with an [UnknownError](./reference.md#error_UnknownError) with a message including "No space left on device". ## `SELECT` Statement - `GROUPING SETS` are not implemented. Queries using these features return a [QueryNotSupported](reference.md#error_QueryNotSupported) error. ## `INSERT` and `REPLACE` Statements - The `INSERT` and `REPLACE` statements with column lists, like `INSERT INTO tbl (a, b, c) SELECT ...`, is not implemented. - `INSERT ... SELECT` and `REPLACE ... SELECT` insert columns from the `SELECT` statement based on column name. This differs from SQL standard behavior, where columns are inserted based on position. - `INSERT` and `REPLACE` do not support all options available in [ingestion specs](../ingestion/ingestion-spec.md), including the `createBitmapIndex` and `multiValueHandling` [dimension](../ingestion/ingestion-spec.md#dimension-objects) properties, and the `indexSpec` [`tuningConfig`](../ingestion/ingestion-spec.md#tuningconfig) property. ## `EXTERN` Function - The [schemaless dimensions](../ingestion/ingestion-spec.md#inclusions-and-exclusions) feature is not available. All columns and their types must be specified explicitly using the `signature` parameter of the [`EXTERN` function](reference.md#extern-function). - `EXTERN` with input sources that match large numbers of files may exhaust available memory on the controller task. - `EXTERN` refers to external files. Use `FROM` to access `druid` input sources.